CVE-2016-3407 in Zimbra Collaboration
Summary
by MITRE
Multiple cross-site scripting (XSS) vulnerabilities in Zimbra Collaboration before 8.7.0 allow remote attackers to inject arbitrary web script or HTML via unspecified vectors, aka bugs 104222, 104910, 105071, and 105175.
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Analysis
by VulDB Data Team • 05/13/2026
The CVE-2016-3407 vulnerability represents a critical cross-site scripting flaw affecting Zimbra Collaboration software versions prior to 8.7.0. This vulnerability encompasses multiple distinct XSS vectors that collectively impact the email and collaboration platform's security posture. The affected versions include Zimbra Collaboration Suite releases that were widely deployed in enterprise environments for email services, calendar management, and collaboration tools. These vulnerabilities were tracked under bug numbers 104222, 104910, 105071, and 105175, indicating the complexity and scope of the security issues within the platform's codebase. The vulnerability affects organizations relying on Zimbra for their email infrastructure, particularly those with large user bases where email systems serve as primary communication channels.
The technical flaw stems from insufficient input validation and output encoding mechanisms within the Zimbra Collaboration platform's web interface components. Attackers can exploit these vulnerabilities by injecting malicious scripts through various input fields, form submissions, or URL parameters that are not properly sanitized before being rendered in web pages. The unspecified vectors suggest that the vulnerability exists across multiple components of the application, potentially including web client interfaces, API endpoints, and administrative panels. This broad attack surface increases the likelihood of successful exploitation and makes remediation more complex for system administrators. The vulnerability operates at the application layer where user-supplied data is processed and displayed without adequate protection against malicious content injection.
The operational impact of CVE-2016-3407 is significant for organizations using affected Zimbra versions, as successful exploitation could lead to complete compromise of user sessions, data theft, and unauthorized access to sensitive email communications. Attackers could execute malicious scripts in the context of authenticated users' browsers, potentially stealing session cookies, accessing confidential emails, or modifying user data. The vulnerability enables attackers to perform various malicious activities including phishing attacks, credential harvesting, and persistent backdoor establishment within the organization's email infrastructure. Organizations may experience reputational damage, regulatory compliance violations, and potential financial losses due to unauthorized access to corporate communications and user data. The attack surface extends beyond individual user compromise to potentially affect entire organizational email systems, especially in environments where Zimbra serves as the primary email platform.
Organizations should prioritize immediate patching of affected Zimbra Collaboration installations to version 8.7.0 or later, which contains the necessary security fixes for these XSS vulnerabilities. System administrators should conduct comprehensive vulnerability assessments to identify all affected systems and ensure proper patch deployment across all email infrastructure components. Network monitoring should be enhanced to detect potential exploitation attempts, and web application firewalls should be configured to filter suspicious script content. Regular security training for users should emphasize the importance of not clicking on suspicious links or opening unexpected email attachments that may contain malicious payloads. The vulnerability aligns with CWE-79, which specifically addresses cross-site scripting flaws in web applications, and represents a common attack pattern catalogued in the MITRE ATT&CK framework under the technique of "T1059.007 - Command and Scripting Interpreter: JavaScript". Organizations should implement proper input validation, output encoding, and content security policies to prevent similar vulnerabilities in their web applications.